RSM River Mechanics Podcast

I grew up in one of North America’s great snow belts…and started my career in Buffalo NYSo, that background and my fascination with sediment transport primes curiosity in ice transport.I’m sure my ice friends would cringe at this, but I sometimes call ice transport as upside down sediment transport.But despite the symmetry of ice and sediment transport, they are separate, complicated, disciplines with little overlapping expertise.Which is why its remarkable, that this episode’s guest is not only is not only world class in both disciplines, but unquestionably the go-to global expert in how they interact.It is fair to say that just about everything I know about how ice effects sediment transport and river morphology, I learned from Dr. Rob EttemaSo I wanted to have Rob on the podcast to talk about the interactions between ice and the other river processes we tend to talk about in this feed. But recognizing that maybe not everyone who listens to this podcast, is initiated into the wild world of fluvial ice dynamics, we start out with some basics of river ice-formation and transport.But then we not only dove into the differences between ice-affected and ice-free rivers, but also how ice affects rivers of different latitudes, depths, and even flow directions.Dr. Rob Ettema retired Colorado State University last year, where he has been a professor since 2015 and continues to work as a research scientist. Before that he taught (and served as Engineering Dean) at the Universities of Iowa and Wyoming.He has edited ASCE’s cold regions journal, and won that society’s Rouse and Einstein (2015) Awards, which is particularly apt as he has written biographical works on the scientists both of those awards are named after.He is well know for his work on ice and scour; the former we talked about at length and the latter we barely touched. But Dr. Ettema, is also one of those researchers, that has multiple self-contained, bodies of work, which have each influenced me enough, that I would have invited him on the podcast for either topic.So in the second half of the conversation, we explore Dr Ettema’s interest in the history of the hydraulic and sediment disciplines, and a genre of literature in which he is second to none: sediment science biography.We talk about lessons from the characters he has written about, including names like Rouse, Einstein, and Radkivi.This will wrap up our Colorado State trilogy.Kind of…we are also releasing some remarkable bonus content with this episode.Jennifer Bountry (Bureau of Reclamation) invited Dr. Ettema and Dr Julien down to the Bureau’s technical service center to teach a short course together. She provided the zoom footage.So I edited a little bit and we are releasing the whole short course on the HEC sediment Youtube channel. If you found the last two episodes interesting, we have about 8 hours, of formal technical content for you to dig into.We’ll link to the playlist in the episode notes and post the This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

Dr. Pierre Julien joined the Colorado State faculty almost 40 years ago, where he worked at CSU’s Engineering Research Center and Hydraulics laboratory. His book, Erosion and Sedimentation, is one of my most common references, and several of the algorithms we have in HEC-RAS (particularly for mud and debris flows) come directly from this text.   But while Dr. Julien’s textbook includes as many partial differential equations and tensors as any other hydraulics text – maybe more – it also includes “rules of thumb” scattered throughout. I have integrated several of these nuggets of actionable, river mechanics wisdom into my field toolbox.  They are heuristics I use regularly to quickly triage river processes and engineering proposals while standing next to a river or sitting in a meeting. So I was curious if these rules of thumb would make an appearance in our conversation…and I was not disappointed.  We do talk some theory.  He shared a couple great metaphors that helped me visualize some of the complex theoretical principles of fluid mechanics better than I had going into the conversation. But Dr. Julien does, also, intentionally develop these decision heuristics and rules of thumb, to help practitioners quickly rule in or rule out alternatives and they popped up throughout our conversation. Dr Julien won the Einstein award in 2004 and the Hunter Rouse award in 2015 the American Society of Civil Engineers lifetime achievement awards for sediment and hydraulics respectively (which is apt as we ended up talking about both the men those awards were named after).  He was also named a Distinguished Member of the American Society of Civil Engineers - their highest honor - in 2022. Dr. Julien has completed projects world-wide with 50 different agencies including world bank and UNESCO and has guided at least 120 masters students and 44 PhDs from 16 different countries.This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

We’re kicking this season off with one of the most prolific researchers in River Science. Dr. Ellen Wohl is a Fluvial Geomorphologist at Colorado State’s Warner College of Natural Resources.As we will discuss, Dr. Wohl has explored and studied rivers on 6 continents (so far).  But she has also focused on river processes in the Colorado front range for more than 20 years, Turning up some important insights from both these scales. I’m not sure if Dr. Wohl leads the fluvial research community in annual words published…But she has to be in the conversation.  In addition to countless peer-review papers she is also prolific in short-form and long-form science communication, publishing frequent blog posts and more than a dozen books.We managed to talk about a pretty wide range of topics, including large river processes, the flood pulse model, the history and current state of restoration research and practice, and a big idea we haven’t interacted with much on this podcast yet: fluvial connectivity.   I first connected with her work through the multi-author review papers she led on the state of river restoration science and practice.  These papers came out twenty years apart, and the second one came out twenty years ago, so I was interested to check in on the state of restoration research and what we’ve learned about this no-longer novel field.But because of her body of work, an interview with Ellen can only touch on a small fraction of her work.  Since I was asking the questions, our conversations mainly followed my interests, and some of her most cited work.  But this link provides a gateway to a broader range of her work:https://sites.warnercnr.colostate.edu/ellenwohl/This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

The peer review process can feel like hazing to a new (or not-so-new) river scientist.  Many excellent practitioners are learning from their rivers every day, but it can feel like if it doesn't get into peer review, it doesn't "count."  So we separated this short segment from my conversation with Dr. Amy East, the Editor-in-Chief of AGU's Journal of Geophysical Research: Earth Surface (and >10 years experience editing high impact journals) to provide a little primmer on how to negotiate the peer review process.  Amy has some really helpful thoughts on how to move from a "Report on a River" to a "Scientific Contribution" that will land well in a journal....and look for the first episode of Season 4 in a few weeks.This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

When HEC hired me to add sediment transport to HEC-RAS almost 20 years ago now, I inherited a set of sediment transport functions that were mostly developed in the early to mid 20th century.  These were – and continue to be – important equations.But when I sat down with the RAS team To talk about the new science I was excited to include in a river mechanics model.I pulled out the same binder I brought to this interview We are wrapping up our third season of the podcast, and our three-part mini series on gravel bed rivers  And talking to the scientist who wrote all the papers in that binder, seems like a fitting way to wrap up both.Dr. Peter Wilcock spent much of his career at Johns’ Hopkins, where he and his team developed the Wilcock and Crowe transport equation and did some of the most important gravel bed transport work that was hitting the journals when I was coming of age in the field.Peter is unquestionably one of the most important contemporary contributors to quantitative gravel-bed transport science and engineering.He won the American Society of Civil Engineers Hans Albert Einstein award in 2008 and is a fellow of the American Geophysical Union.And we talked a lot about that fundamental, early work, that is just kind of part of established gravel bed transport theory these days.But 10 years ago he moved to Utah State, improving his proximity to classic gravel bed rivers, and in the years since I put that binder together of his paradigm shifting work, Peter has been very intentional about translating his science into practical channel design methods, particularly for restoration channel designs.So we talked about both…starting out with more of the channel design topics and then moving into his classic findings. The Link to Peter's Stream Assessment and Design Class Materials (including iSURF) that we talk about is here:https://qcnr.usu.edu/wats/programs/short-courses/sediment-transport/course-materials-2022We also talk about Ron Copeland's channel design method.  We made a short video with Ron on that method which is good background for this episode here:https://youtu.be/ykJ3FA39p0gRon's podcast is here:https://podcasts.apple.com/us/podcast/ron-copeland-on-analytical-channel-design-the-laursen/id1650989239?i=1000587444097Finally, we also have an interview with Joanna Curran (the Crowe in Wilcock and Crowe) which makes a good companion to this episode here:https://podcasts.apple.com/us/podcast/joanna-curran-on-gravel-bed-rivers-wilcock-and-crowe/id1650989239?i=1000589529286This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

tDr. Power is a food web ecologist at UC Berkeley, where she leads the Power lab which has compiled careful, long term data sets in the Angelo Reserve in Northern CA.In addition to her early work, in Panama and the Ozarks - which we touch on briefly - Dr. Power’s  multi-decadal data sets on the Eel River, have yielded remarkable findings about how food webs function in gravel bed rivers…and spoiler alert, it sometimes involves the sorts of things we tend to talk about here…like the gravel - and how it transports.While this is a physical science podcast, I hoped to include interviews with river Ecologists from the beginning particularly ecologists who make careful observations at that interface of physical and biological processes. And I always hoped I could kick that emphasis off with Dr. Power.I teach an Ecogeomorphology module in one of our classes here at HEC and I always lead that with the Eel river story she shares About 20 minutes into this episode.That Eel river story was one of the early influences that got me interested in the ecological interactions with river mechanics processes.I also asked Mary about a couple of Ecological models and categories, that have corollaries in geomorphology.  So we talked about disturbance, alternative stable states as well as the Box model and the Ideal Free Distribution, which are just really helpful ideas for anyone who is interested in rivers.Dr. Power was inducted into the National Academy of Sciences in 2012.Links: Serengeti Rules:     https://www.pbs.org/wnet/nature/serengeti-rules-dhbtnm/19906/Disturbance and Recover of Algal Assemblage on OK Stream         https://www.jstor.org/stable/2425975Resource Enhancement: Armored Catfish, Algae, and Sediment     https://www.jstor.org/stable/1937361Episode Photo: Eel RiverThis series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

Dr Alain Recking has quantified gravel bed transport with just about all the tools available to our discipline.In addition to substantial field work- Dr. Recking has done some important and influential flume experiments.We have talked and will talk about hiding and armoring quite a bit in this podcast, because they are difficult ideas, that are hard to measure and simulate,  and critical to gravel bed processes.But Dr. Recking’s contributions to this vertical sorting conversation destabilizes armoring theory a bit…kind of literally,He found that in high gradient channels,  at equilibrium flows, vertical sorting doesn’t necessarily reach an equilibrium, but can be episodic, which is important because it leads to the pulsed transport processes.And the story he tells about how he discovered this...is just kind of narrative science at its very best.The other characteristic of Alain’s work that I think is remarkable is his a knack for pulling together immense data sets (often including substantial data from the American West) in order to pose important quantitative questions on the meta-analyses scale. And so we talked about how this lead to his gravel-bed flow-resistance  work and – what I consider – the most important sediment transport equation,  since the Parker/Wilcock-Crowe generation of innovation. We also talk about Bedload Web, where he has collected many of the measurements he used to to these analyses: https://en.bedloadweb.com/Dr. Recking works for INRAE – The French National Research Institute of Agriculture, Food, and Environment a research consortium  focused on sustainable development in those arenas. This week, on the RSM River Mechanics podcast,  we talk high gradient sorting, quantitative meta-analyses with Alain Recking.We also posted videos clips with his experiments here:  https://youtu.be/jKFlMAkD7qoThis series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

A couple years ago, my agency asked me to write some guidance on sediment modeling, so, I reached out to the morphological modelers I knew, and particularly the model developers who write the morphological model code other people use.I asked them about the common failure modes they have seen and best practices they teach, and realized we had all essentially spent a decade or two, learning the same principles. So when the US federal agencies held their periodic Federal interagency sediment conference (SEDHYD) last year, I invited three of the model developers I have learned from over the years (Alex Sanchez, Gary Brown, and Blair Greimann), to participate in a panel discussion on their lessons learned.And the panel was much more popular than we expected.  It turns out, there’s appetite conversations like this.  So, I turned on the mics and we did a little editing, and we’re running it here.Here are brief bios for our guests.:Gary Brown did his graduate work at the university of Florida and works at the Coastal and Hydraulics Lab which is part of ERDC, the Corp’s major R&D center in Vicksburg Mississippi.   He’s been developing sediment models for 29 years including SEDLIB, a set of sediment algorithms that are called by ERDC’s hydraulic model, ADH or Adaptive hydraulics.  Alex Sanchez sits in the office next to me.  For the last 9 years, he has worked here at HEC and spearheaded the work to add 2D sediment to HEC-RAS which includes a novel formulation for the sub-grid approach.  But actually Alex started developing sediment models at ERDC’s Coastal and Hydraulics Lab where he worked for 8 years, while working on the Coastal Modeling System which is still used for Corps of Engineers coastal applications.  Blair Greimann got his PhD from the University of Iowa and worked at the Bureau of Reclamation’s Technical Service Center in Denver for more than 23 years, before his recent move to Stantec.  While working at the Bureau Blair led the development of SRH-1D and applied this model to a range of projects including the Matilija and and Klamath Dam removals.Finally, we were lucky enough to have Doug Shields moderating this session so you will hear from him in the breaks between the four sub-topics.  Dr. Shields, worked for more than 20 years at the Sedimentation Lab of the Agricultural Resource Center in Oxford MS and 10 years at ERDC and has taught at both Tennessee State and Old Miss and we were fortunate to draw Doug as a moderator.  (Note: I did not mic Doug, but wanted to keep his thoughtful and winsome transitions, so his sound quality is not at the same level as the rest of the recording).After Doug and I introduced the session you will hear from Blair Greimann, Alex Sanchez, me again, and Gary Brown in that order.The conference paper associated with this session is here:https://www.sedhyd.org/2023Program/1/157.pdfThank you to the SEDHYD organizers (including but not limited to ) for hosting this conversationThis series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

I’ve heard people call Tony the godfather of Sediment Transport Modeling and - as you’ll hear in our conversation - he very well may be the first person to use a computer to answer an engineering scale sediment question.But most people about my age and older, know Tony for developing the first generalized sediment model.  He was part of the original team here at the Hydrologic Engineering Center (HEC) where he developed HEC6, a 1D sediment transport model that was industry standard for decades.Now, if you get a couple of model developers together, we could talk all day about transport equations and algorithms.And we did.  But I am going to turn most of that technical modeling content, into videos to run on the YouTube page and in the RAS manual.This conversation focuses on Tony’s insights that I think have the broadest application.Because one of the things that make’s Tony’s career so interesting, transcends modeling.After Tony worked at HEC, he moved to the Corp’s lab in Mississippi  and then started Mobile Boundary Hydraulics,  which was the premier 1D sediment modeling shop for decades.But if you follow the timeline, that means that Tony (who only recently, actually, retired) has been predicting river processes for more than 60 years.He is one of the few people who has seen the end of his 50 year project life predictions.And all numerical modeling is – fundamentally - is exposing your mental models, to quantitative feedback and observational falsification.It’s a learning loop with Rivers… …and no one has been working that learning loop longer than Tony.I essentially sit in that seat Tony invited as the sediment modeling specialist here at HEC.  But Tony actually had a more direct influence on me than that.About 20 years ago, when we decided to put 1D sediment transport into HEC-RAS, we got a grant to bring Tony back to HEC and he spent 5 months essentially teaching me how to develop a generalized sediment model.There was a point in my life, where almost everything I knew about sediment came from Tony, and his insights and categories still frame the way I look at rivers.When I first imagined this podcast, it included a conversation with Tony, reproducing some of those formative conversations we had over the years.So in this conversation we talk about the sediment modeling origin story and some of the modeling principals he’s famous for but we also just talk about the river processes and projects that built his intuition and/or surprised him over the years.(Photo Credit: Tony on the Arroyo Pasajero – provided by Dr. Ron Copeland) This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248

Dr. Jim Selegean is the Sediment Transport Specialist at the Corps Detroit District where he studies the rivers and sediment loads into the great lakes as well as inland costal processes. He is also a professor at Wayne State in Detroit. And that joint position has helped him mentor many young scientists and engineers  throughout the years, geomorphically trained Hydraulic engineers who not only currently populate the Detroit district but also includes what we call the Detroit diaspora,  Jim’s protégées who fill important sediment and river mechanics leadership positions across the Corps. We recorded this podcast in the lab and field investigation shop  Jim built on the Detroit River, which is the most complete and productive corps sediment lab I know of outside Mississippi.  Within my agency, I don’t know anyone who has quite the grasp of the river mechanics cannon, as Dr. Jim Selegean of the Corps of Engineers’ Detroit District. But he also metabolizes as much contemporary literature as anyone I know in our agency, which manifests in a weekly email he sends out, with the 8-10 best papers he read from current journals that week and a 3-4 sentence summary of his favorites. (If you’d like to get on that list, you can reach out to him at [email protected]) One of the things I found helpful in my Ecology education was a Foundations of Ecology text (https://a.co/d/9zjK1wg) which compiled the classic papers in ecology and commentaries by noted contemporary scientists whose work built on that particular area of reflection. Years ago I pitched this type of book to Jim, suggesting we should try to write it of our field. He just laughed at me, wisely predicting that neither of us nearly the time required.But when I stared to design this podcast, I knew I wanted to recording a kind of “pitch meeting” for the papers we would each include in that compilation. But, Jim is also one of the most fun people I work so we tried to make it a little more entertaining…and a little competitive, by giving it a draft format (like picking players for a schoolyard football game). There was some strategy…that mostly went Jim’s way. Feel free to find the posts associated with this podcast on LinkedIn or X to offer your choices…maybe we’ll do another one. But for now, welcome, to the RSM River Mechanics Podcast…Classic Paper Draft.This series was funded by the Regional Sediment Management (RSM) program.Mike Loretto edited the first three seasons and created the theme music.Tessa Hall is editing most of Season 4.Stanford Gibson (HEC Sediment Specialist) hosts.Video shorts and other bonus content are available at the podcast website:https://www.hec.usace.army.mil/confluence/rasdocs/rastraining/latest/the-rsm-river-mechanics-podcast...but most of the supplementary videos are available on the HEC Sediment YouTube channel:https://www.youtube.com/user/stanfordgibsonIf you have guest recommendations or feedback you can reach out to me on LinkedIn or ResearchGate or fill out this recommendation and feedback form: https://forms.gle/wWJLVSEYe7S8Cd248